Pro-aging factor in blood impairs memory

Nature Medicine

July 7, 2015

A circulating protein in the blood that increases with age and may impair learning and memory is reported in a study published in Nature Medicine. The findings, from research in mice and humans, suggest that this protein may be targeted to prevent age-related memory loss.

A progressive decline in learning and memory, as well as a reduction in the birth of new neurons, is associated with aging. Previous work has suggested that the transfusion of blood from young mice can partially reverse memory impairments and improve neuronal function in the aged brain. The identification of factors that accumulate in the blood with aging and impair memory may enable interventions to prevent memory loss. A protein associated with immune function, β2 microglobulin (B2M), accumulates in the blood; however, its role in mediating age-related impairments in the adult brain has not been investigated.

Saul Villeda and colleagues found that B2M is elevated in the blood of elderly individuals and increases with age in both mice and humans. Mice lacking B2M do not develop age-related memory loss, while injection of B2M, either systemically or directly into the brain of young mice, impairs performance in learning and memory tasks and reduces the growth of newly-born neurons. In an independent cohort of young mice, these learning and memory impairments induced by B2M were no longer apparent after 30 days, suggesting that the protein’s effects on cognitive decline are potentially reversible.